This disclosure relates to drag conveyor that is used, for example, with a welding system and welder used to secure fasteners to stampings.
The production of complex assemblies such as vehicles, appliances, consumer goods, and furniture often requires the fabrication of welded subassemblies, such as sheet metal workpieces with one or more welded fasteners. In the production of an assembly as complex as a vehicle, there can be a considerable quantity and variety of such sheet metal workpieces that are produced in a stamping operation for later welding in batches to produce the required welded subassemblies. A machine operator must remove a randomly oriented and sometimes interlocked sheet metal workpiece from the storage bin before loading it into the welding machine. A second component is then added manually or by automation in preparation for welding. In the case of resistance welding, two electrodes close upon the workpiece and second component before applying force and a high current necessary for completing the resistance weld. The finished subassembly is then removed from the machine in preparation for repeating the welding operation.
As automotive component production costs continue to be pressured lower, labor productivity is under increased scrutiny. The common direction in the industry is to replace labor with significant automation. To be competitive, it is important to maximize the productivity of both the equipment and operator. Much effort is being directed to address this challenge by building equipment with elements such as one or more fixtures to orient the workpiece or complex vision systems that permit a robot to accurately grasp and position the workpiece. Such systems can be challenging to set-up and may require specialized and costly skills to configure, troubleshoot and maintain. The problem this approach has created is equipment that is too hard for many customers (or specific plants) to set-up, operate and maintain. Some cannot access skilled labor, or they do not have enough complex equipment to justify investment in skilled labor and tools. Excessive sophistication may limit the operational reliably in the production environment. The complexity also increases the capital cost of the equipment and the inventory of spare parts to keep it in operation.
It is desirable to use equipment that is simple to configure, operate, troubleshoot, and maintain. It is also desirable to minimize the equipment changeover time while also minimizing its complexity.